1. Field of the Invention
The invention relates to a device for the separation of soiled plastic products, having different softening points, which are comminuted, purified and dried through an intermediate storage with a feed device disposed above a heated steel tape and where the plastic materials are placed onto the steel tape in a thin layer, wherein the steel tape is furnished with one or several vibrators and where the vibrator is just attached SUCH that the free-flowing plastic particles with the different softening points are transported over the steel tape and are caught in different catch devices.
2. Brief Description of the Background of the Invention Including Prior Art
Such methods are used for the reprocessing and reutilization heavily soiled plastic products, such as is described, for example, in the German Patent DE-PS 25 25 750.
According to a conventional separating device, taught in the Soviet Union Patent SU 12 84 605 A1, the plastic particles to be separated are placed with the aid of a hot air stream onto a vibrating but otherwise thick steel bands and the different plastic particles are transported in opposite directions with the aid of the vibration forces. The support and transporting air is heated such that the temperature of the plastic particles remains below the softening temperatures. It is intended with this that the plastic particles do not adhesively attach to steel tape. Based on this step the different plastic particles are to be moved on different fly paths. This is associated with the disadvantage that the steel tape can be covered only in one layer with the plastic particles. In case of multi-layer covering of the steel tape, the fly paths of particles are interfered with. A further disadvantage of the older device is associated with a situation that the hot support air swirls the plastic particles and consequently renders a separation of the individual plastic materials more difficult.
The separation of comminuted plastic waste materials including materials with a higher specific weights and lower specific weights as employing a washing liquid is described in the German Patent DE-PS 28 04 729. In this case the separation is performed by a wet-sinking method. (U.S. patent application Ser. No. 07/406,154, filed Sep. 12, 1989).
In contrast, soiled different plastic products are generated, where the specific weights are closely together such that wet-sink separation after the comminution is not possible. Thus, soiled plastic formed parts such as bottles, boxes and the like, are generated, which are made of polyester (PET) and polyvinylchloride (PVC). The two materials have nearly the same specific weight.
In order to separate such materials having different softening points but nearly the same specific weights such as recited and also for other materials, such materials are placed onto conveyor belts before the recycling and are manually separated. Based on a human error, even in this case, a hundred percent separation is not possible. In order to reduce error sources an X-ray beam radiation method has been employed. The beams can detect plastic parts containing chlorides and are thus capable to allow a separation of polyvinylchloride (PVC) from polyester (PET). Apart from the high cost and the danger of the radiation for the personnel, even in this case a hundred percent separation is not possible. For example, the formed an molded parts are furnished with adhesive labels, and in this case the radiation cannot any longer capture the plastic material such that also materials without chloride components are treated like polyvinylchlorides.
The German Printed Patent Document DE 37 22 777 A1 teaches a device for the sorting of thermoplastic, plastic parts from stream of mixture, employing a heated circulating steel tape. Parts of the plastic particles adhesively adhere to the steel tape. The particles not adhering are separated. According to this older device, the plastic parts to be separated are transported through a cascade arrangement in steps. The cascade causes not only a high in expenditure investment but also it cannot be prevented that the parts of the plastic to be separated remain always at the surface of the flow of the mixture and consequently these parts do not pass through the surface of the steel tape. A secure separation is thus not assured.